Revert and replace #4127 -- Funk jood, round deux (#4481)

Reverts the new chemicals and their effects as implemented in #4127 due to their unnecessary severity.

Replaces the reverted mechanics with new mechanics which seek to accomplish a similar thing. Mobs now have an nutrition_attrition_rate factor, which is a multiplier describing how fast they grow hungry. By default, the multiplier is 1. Only eating healthy/chef food will see to it that said multiplier remains at 1.

code/modules/mob/living/carbon/human/life.dm

@@ -933,7 +933,7 @@
 
 	// nutrition decrease
 	if (nutrition > 0 && stat != 2)
-		nutrition = max (0, nutrition - nutrition_loss)
+		nutrition = max(0, nutrition - (nutrition_loss * nutrition_attrition_rate))
 
 	if (nutrition > max_nutrition)
 		if(overeatduration < 600) //capped so people don't take forever to unfat

code/modules/mob/mob_defines.dm

@@ -111,7 +111,8 @@
 	var/drowsyness = 0.0//Carbon
 	var/charges = 0.0
 	var/nutrition = 400.0//Carbon
-	var/nutrition_loss = HUNGER_FACTOR//How much hunger is lost per tick. This is modified by species
+	var/nutrition_loss = HUNGER_FACTOR //How much hunger is lost per tick. This is modified by species
+	var/nutrition_attrition_rate = 1   // A multiplier for how much this specific mob loses per tick.
 	var/max_nutrition = 400
 
 	var/overeatduration = 0		// How long this guy is overeating //Carbon

code/modules/reagents/Chemistry-Reagents/Chemistry-Reagents-Food-Drinks.dm

@@ -58,13 +58,20 @@
 	taste_mult = 4
 	reagent_state = SOLID
 	metabolism = REM * 4
-	var/nutriment_factor = 12 // Per unit
+	var/nutriment_factor = -(REM * 4)/BASE_MAX_NUTRITION // Per removed in digest.
 	var/blood_factor = 6
 	var/regen_factor = 0.8
 	var/injectable = 0
+	var/attrition_factor = -0.1 // Decreases attrition rate.
 	color = "#664330"
 	unaffected_species = IS_MACHINE
 
+/datum/reagent/nutriment/synthetic
+	name = "Synthetic Nutriment"
+	id = "synnutriment"
+	description = "A cheaper alternative to actual nutriment."
+	attrition_factor = (REM * 4)/BASE_MAX_NUTRITION // Increases attrition rate.
+
 /datum/reagent/nutriment/mix_data(var/list/newdata, var/newamount)
 	if(!islist(newdata) || !newdata.len)
 		return
@@ -101,6 +108,7 @@
 /datum/reagent/nutriment/proc/digest(var/mob/living/carbon/M, var/removed)
 	M.heal_organ_damage(regen_factor * removed, 0)
 	M.nutrition += nutriment_factor * removed // For hunger and fatness
+	M.nutrition_attrition_rate = Clamp(M.nutrition_attrition_rate + attrition_factor, 1, 2)
 	M.add_chemical_effect(CE_BLOODRESTORE, blood_factor * removed)
 
 
@@ -3545,58 +3553,3 @@
 	glass_icon_state = "crocodile_glass"
 	glass_name = "glass of Crocodile Guwan"
 	glass_desc = "The smell says no, but the pretty colors say yes."
-  
-//Preservatives
-
-/datum/reagent/nutriment/badfood //This is just a base. It shouldn't exist or be used anywhere but just in case, I added names.
-	name = "Experimental Preservative"
-	id = "badfood"
-	description = "Some... strange chemical. You can swear it's moving."
-	nutriment_factor = 50
-	color = "#000000"
-	taste_description = "liquid heart attack"
-	metabolism = REM * 1 //Metabolises slower
-	var/damagemul = 0.5 //How much damage to deal to the heart per unit digested
-
-/datum/reagent/nutriment/badfood/affect_ingest(var/mob/living/carbon/human/M, var/alien, var/removed)
-	if(istype(M))
-		var/obj/item/organ/F = M.internal_organs_by_name["heart"]
-		if(istype(F))
-			F.take_damage(removed * damagemul,1)
-	..()
-
-/datum/reagent/nutriment/badfood/palmoil
-	name = "Palm Oil"
-	id = "palmoil"
-	description = "Palm oil is a common preservative used in packaged food, and is seriously unhealthy for you much like everything on this station."
-	nutriment_factor = 30
-	color = "#f4ce42"
-	taste_description = "oily fat"
-	damagemul = 0.15
-
-/datum/reagent/nutriment/badfood/shortening
-	name = "Shortening"
-	id = "shortening"
-	description = "Shortening, also known as hydrogenated vegetable oil, is a preservative commonly used in packaged food. Usually made from vegetables."
-	nutriment_factor = 20
-	color = "#e2d4c9"
-	taste_description = "greasy fat"
-	damagemul = 0.05
-
-/datum/reagent/nutriment/badfood/hfcs
-	name = "High Fructose Corn Syrup"
-	id = "hfcs"
-	description = "A cheap, easy to produce, unhealthy alternative to real sugar."
-	nutriment_factor = 20
-	color = "#c66119"
-	taste_description = "sweetness"
-	damagemul = 0.1
-
-/datum/reagent/nutriment/badfood/msg
-	name = "Monosodium Glutamate"
-	id = "msg"
-	description = "Monosodium glutamate, also known as MSG, is a cheap flavor enhancer similiar to sodium. Causes chinese restaurant syndrome."
-	nutriment_factor = 5
-	color = "#eaf1fc"
-	taste_description = "flavoring"
-	damagemul = 0.05